Vulcanizing apparatus



W. J. JARRATT ET AL VULCANI Z ING APPARATUS Filed Dec. lO,

lll/IZ May 6, 1930.

Patented May 8, 1930 UNITED STATES PATENT OFFICE WALTER J'. JABRATT AND FRANK E. HABTMAN, 0F CHICAGO, ILLDSI'OIS vULcANIzINe APPARATUS Application filed December` 10, 1927. Serial No. 239,016.

Our invention relates to an ap aratus for treating rubber articles and has or one purpose to provide means for heat treating or vulcanizing rubber tires or casings.. Another object is to piovide for the treating or vulcanizing of the interior of a tire or casing by the employment of a circulation of beate air or other aseous or vaporous heat conducting media. ther objects will appear from time to time. in the course of the specification and claim.

We illustrate our invention more or less diagrammatically in the accompanying drawings, wherein- Figure 1 is a schematic view of the entire system;

Figure 2 is a longitudinal section through the air heating means;

Figure 3 is a section on the hne 3-3 of Figure 2;

Figure 4 is a section on the line 4 4 of Figure l;

Figure 5 is a wiring diagram of the heatlng element; and

Figure 6 is a longitudinal section through the heating bag or container employed.

Like parts are indicated by li e symbols throughout the specification and drawm s. n

Referring to Figure 1 A generally indicates a vulcanizer casing, herein shown with the ground engaging supporting members'A1 and the upward lateral extensions A2 having the interior downward extensions Aa which preferably conform to the outer shape'of a tire or casing. A4 diagrammatically indicates an outer tire casing into the ho low of which is inserted the ba B, of rubber or any other suitable materia A5 indicates any suitable clamping means whereby the tire and bag are clamped to ether against the vulcanizer casing A and etween the extensions A. A indicate resistance elements whereby the vulcanizer casin may be heated, and A" indicates the conductive circuit therefor.

The bag B is shown as having in communication therewith at the opposite ends, the air ducts B1 B2. Referring to the air circuit of which the bag B forms a part C is any suitable fan or blower chamber within which the fan C1 is actuated as by the motor C. The air is forced by the fan through the passa e C3 to the heating element C, which is escribed in greater detail below. The heated air passes by the passage C5 to the air inlet Bl and thus throu h the bag B. The air escaping-through t e air outlet B2 passes through the duct C and thus back to the fan C.

In Figure 6 we illustrate a desirable form of bag B in which the ducts B1 B2 terminate, within the bag, in outwardly flared portions B1o in which are the air slots B11. Associated with the portions B10 are ballles B12 Which may be connected for example by the intermediate connector or brace B. It will be understood that the construction above described insures a circulation of the air or other heating medium along the outer `wall of the bag B.

D indicates an air compressor, the details of which form no part of the resent invention. The air supplied by t e compressor passes by the passage D1, having the valve D to the pressure or diaphragm control valve D3 which is shown as having associated with it the diaphragm D4, the lever D anu the adjustable counterweight D". D indicates any suitable Hap or one way valve, adapted to permit the passage of air from the compressor to the passage C, and adapted to prevent escape of air in the opposite direction. DB is any suitable communicating member, herein shown as a T, whereby the connection is obtained between the passage from the air compressor to the passage C".

Referring more particularly to the heating member generally shown as C, it is herein shown as including the end member C1 with which communicates the air inlet assage C'. The member C7 is also formed wit a projection C8, associated with which is the po off valve C", or any suitable pressure re ease mechanism, adapted to permit the esca e of air when the pressure-within the close circuit exceeds a predetermined maximum. C1 is the opposite end member of the heating element, the two being connected for example by the pipe C, Extendin from the end member C1o is the air outlet uct C5. It may also have associated with it any suitable temperature indicating member herein shown as thermometer C12 with the exposed lstem Mounted within the pipe C11 is a heating member consisting of a central rod E along which are mounted a plurality of discs E1, each disc being provided with a plurality of perforations E2. Passing through these perforations are the resistance coils or wires E".

In the practice of our invention we find it desirable, in order to maintain an accurate temperature control, to employ two or more resistance elements each of which may include one or more coils.

In the wiring diagram we indicate a primary coil or resistance circuit E, having the conductive connections E6 E7. The secondary coil or resistance member E8 is provided with the conductive connections E9 E1". The main actuating circuit is shown as at E11 E12. E indicates any suitable multiple point switch, whereby when the switch is set at the full line position, both resistance circuits are closed, and whereby when it is set at the dotted line position, the main or primary resistance circuit is open.

In order to provide automatic operation we may employ any suitable thermostatic means whereby, when a. predetermined temperature has been reached the primary circuit is broken and the secondary circuit may be broken at the same time, or shortly thereafter. Subsequently, the secondary coil is thermostatically cut in or out, in response to temperature fluctuations, whereby the temperature of the heating element is maintained at or about a predetermined norm.

The use and operation of our invention are as follows:

In vulcanizing or treating rubber tires or casings, it is customary to nosition a casing in an outer mold which must be heated, in case it is the exterior of the tire which is to be vulcanized, and which may be heated when the interior is vulcanized or cured. In the latter case, the most efiicient method of applying the heat to the interlor of the tire is to deliver it directly to the zone to be heated or treated. In our apparatus and process we employ as a source of interior heat a bag or container which conforms to the interior shape of the casing. The use of such a bag is already known, but the novelty of our rocess and apparatus consists in heating this bag by circulating hot an' therethrough. The process and apparatus may be analyzed as follows: The heating circuit includes the bag itself, a blower,yherein shown as a motor driven fan, a heatinguchamber, and the necessary connecting passages. The air in the circuit is raised to and maintained at a predetermined pressure by the use of any suitable air compressor. his

compressor delivers air to the system through a check valve which permits movement of the air only into the system. We also provide, in the admission passage, any suitable means, for example a pressurevdiaphragm valve, whereby air from the compressor will be admitted to the circuit in response to a drop in the general pressure of the circuit beneath a predetermined minimum pressure. In the operation of the system the compressor is actuated and raises the pressure above the predetermined minimum. The compressor then becomes inoperative and further air is admitted to the system only in order to raise the system pressure to normal, in case it drops below the said predetermined minimum.

Assuming that the pressure in the system is at or above the predetermined minimum, the fan circulates the air within the system and does not itself build up pressure except, of course, the local pressure necessary to overcome the static friction of the system. Thus if the air in the system has to be moved through several feet of pipe, a certain pressure is needed to effect the circulation, and this pressure the fan does supply. In order to reduce it to a minimum, the passages are so shaped and are of such size and proportion as to lighten the work of the fan. Thus passages of relatively large cross-section and h a minimumof sharp turns are prefera e.

We `do not wish to be limited to any particular type of heater but we herein illustrate a passage along which are spaced porcelain insulating discs with apertures through which pass the heating coils. The air passes through the passage and through the apertures in the discs and Vthrough and along the heating coils. Obviously gas or other heating means might be employed, for heating the air or other media, in case electricity is not available or desirable.

In order to govern the temperature in the system we prefer to employ a heating element having two or more separate coils or divisions. By the employment, for example, of a two point switch, I may actuate the entire heating element when the device is first set in operation. When the temperature of the heater reaches a predetermined normal, we can then cut out part of the heater. Thus when employing two coils we can initially heat both and then cut out one of them. In the preferred form herein shown we employ a large coil and a small coil, the large coil being cut out after a predetermined temperature is reached. The small coil may be o erated continuously, but preferably is emp oyed as a regulator, being thermostatically switched on and off, in response to temperature uctuations. I prefer to provide thermostatic regulating means whereby the supplemental coil is heated when the temperature dro s below the predetermined normal and W ereby the circuit is broken when the temperature exceeds the predetermined normal. It will be realized of course that a wide variety of mechanisms may be employed, but we prefer to employ some automatic means whereby the heating device is maintained at or close to a predetermined norm.

In order to protect the system against undue pressure we may employ a pop oli valve or any suitable release, whereby an excess pressure is released without damage to the mechanism or to the operator.

The heating bags employed may be of rubber, but are preferably treated to` prevent deterioration by the passage of heated air. As shown in Figure 6 the bag is provided with bailies, whereby the circulating medium is direted along the inner face of the wall of e ag.

One reat advantage of our method is the possibi ityv of independent control in temperature and pressure. In the system wherein steam is em loyed as the heating medium a given desire temperature may necessitate a dangerous steam pressure, and an increase in temperature, to heat a given condition, may not only result in an extreme pressure,

but may cause an explosion, a destruction of the device and damage or death to an operator. Air has a low specific heat 1.38, and if for any reason hot air is discharged on the system itcools so rapidly on eXpansion that there can be no damage to the operator. A steam explosion, on the contrary, may result in scaldlng the operator.

A further advantage of the employment of air in such a circuit is in the elimination of the condensation of Water in the bag or in the passages.

We claim:

In'an apparatus for applying heat for vulcanization and the like, an iniiatable air receptacle adapted to be opposed to the work,

a normally closed air circuit in communication with such receptacle, means for raising the pressure of said circuit to a predetermined normal, means for circulating the air o in such circuit through said receptacle, in-

cluding a fan chamber included in said circuit, a fan in said chamber, and means for im arting to it a generally constant rotation.

igned at Chicago, in the county of Cook and State of Illinois, this 5th day of December, 1927.

WALTER J. JARRATT. FRANK E. HARTMAN. 

